Nutritional Advice El Mondo

Vitamin D

Scientific studies (review articles) on the relationship between vitamin D and disease prevention:
One swallow does not make a summer. A famous Dutch saying that could not be any more obvious. Just because one single scientific study about a certain topic makes certain claims, it does not necessarily mean it is true. On the other hand, a review article (a collection of scientific studies on a certain topic) of randomized, placebo-controlled double blind clinical trials (RCTs) will answer the following question:
"Do taking dietary supplements make sense?" Yes for a positive conclusion and no for a negative conclusion.

One swallow does not make a summer. A famous Dutch saying that could not be any more obvious. Just because one single scientific study about a certain topic makes certain claims, it does not necessarily mean it is true. On the other hand, a review article (a collection of scientific studies on a certain topic) of cohort studies or case-control studies will answer the following question:
"Should I change my diet?".

  1. 400 IU/day to 300,000 IU vitamin D supplementation improves handgrip strength in postmenopausal women
  2. 25(OH)D concentration increases by 2 nmol/L for every 100 IU vitamin D in adult
  3. 10 μg/d vitamin D food fortification increases vitamin D levels in populations
  4. Low vitamin D level increases wasting among children
  5. Vitamin D supplements improve symptoms of knee and hip osteoarthritis among adults
  6. Vitamin D deficiency is associated with greater severity of COVID-19 infection
  7. Vitamin D deficiency increases infection risk, mortality and severity COVID-19 infection
  8. Vitamin D supplements improve WOMAC pain and function in patients with knee osteoarthritis
  9. Calcium + vitamin D supplementation reduce hip fracture in postmenopausal women
  10. Vitamin D supplements should be added to treatment protocols of COVID-19 disease
  11. Vitamin D deficiency increases severity of COVID-19
  12. Low serum vitamin D levels increase COVID-19 infection
  13. A low vitamin D level increases severity of hepatitis C virus infection
  14. Severe vitamin D deficiency ( 10 ng/mL) increases mortality in patients with sepsis
  15. 800-1,000 IU/d vitamin D3 reduces fracture and fall risk among elderly
  16. Vitamin K + D supplement increase bone mineral density
  17. Post-diagnosis calcium, vitamin C, D or E decreases cancer mortality
  18. High serum vitamin D level is not a protective factor for latent tuberculosis infection
  19. Micronutrient supplementation improves quality of life in patients with pulmonary tuberculosis
  20. Tuberculosis is highest among HIV-positive individuals with severe vitamin D deficiency
  21. Vitamin D improves fasting glucose among patients with chronic kidney disease
  22. Maternal vitamin D deficiency during pregnancy increases low birth weight
  23. High prenatal vitamin D level reduces risk autism-related traits later in life
  24. 15 minutes/week sunlight exposure decreases risk of Parkinson's disease
  25. 88 µg/d vitamin D supplementation reduces type 2 diabetes
  26. Omega-3 fatty acids + vitamin E or D reduce gestational diabetes
  27. No association between vitamin A, C, D, E and lycopene and risk of non-Hodgkin lymphoma
  28. Daily 10 mcg dietary intake of vitamin D decreases risk of pancreatic cancer
  29. Vitamin D level of 25 to 35 ng/mL decreases risk of dementia and Alzheimer's disease
  30. A high vitamin D level increases walking speed among older adults
  31. Low vitamin D status is related to poorer cognition in healthy adults
  32. 75-87.5 nmol/L vitamin D decrease mortality in the general population
  33. Higher levels of gestational vitamin D reduce multiple sclerosis in offspring
  34. Decreased vitamin D levels and increased BMI increase pediatric-onset MS
  35. High dietary vitamin B9, D, B6 and B2 intake reduces risk of colorectal cancer
  36. Vitamin D supplementation during pregnancy or infancy reduces adiposity in childhood
  37. Severe vitamin D deficiency (20 ng/mL) increases risk of early spontaneous pregnancy loss
  38. Vitamin D supplementation alone during pregnancy reduces risk of preterm birth
  39. Vitamin D fortification reduces vitamin D deficiency in healthy children
  40. 100 IU vitamin D/d increase serum 25-hydroxyvitamin D with 1.0 nmol/L in children 2-18 y of age
  41. Vitamin C and D reduce blood pressure in patients with type 2 diabetes
  42. Vitamin D deficiency increases blindness in people with diabetes
  43. Serum vitamin D concentrations between 40 and 75 nmol/L reduce hypertension in adult
  44. Low vitamin D level increases acne
  45. Serum vitamin D ≥75 nmol/L reduces risk of allergic rhinitis in men
  46. Vitamin B12, D and E reduce eczema
  47. Low vitamin D level increases asthma in children

XXXXXXXXXXXXXXXXXXXX

  • Vitamin D is a hormone precursor that is present in 2 forms. Ergocalciferol or vitamin D2, is present in plants and some fish. Cholecalciferol or vitamin D3, is synthesized in the skin by sunlight, at UVB wavelengths of 290-315 nm.
  • Exposure of human skin to solar UVB radiation leads to the conversion of 7-dehydrocholesterol to previtamin D3 in the skin. Previtamin D3 is then rapidly converted to vitamin D3 by temperature- and membrane-dependent processes. The vitamin D binding protein transports the vitamin D3 to the liver where it undergoes hydroxylation to 25(OH)D (the inactive form of vitamin D) and then to the kidneys where it is hydroxylated by the enzyme 1-alfa-hydroxylase to 1,25(OH)D (the active form of vitamin D).
  • Prolonged sun exposure does not result in the production of excess quantities of vitamin D3 to cause intoxication. The reason for this is that previtamin D3 and vitamin D3 efficiently absorb sunlight and are converted to a multitude of other photoproducts, including lumisterol, tachysterol, suprasterols and toxisterols.
  • Skin that is exposed to sunshine indoors through a window will not produce vitamin D.
  • Cloudy days, shade, having dark-colored skin and skin of an elderly also cut down on the amount of vitamin D the skin makes.
  • Sunscreens with a sun protection factor of 15 or more block 99% of dermal vitamin D synthesis.
  • Vitamin D play a role in maintaining the immune system, helping maintain healthy skin and muscle strength.
  • 15-30 minutes of sunshine three times weekly is enough to produce the body's requirement of vitamin D. The sun needs to shine on the skin of your face, arms, back or legs (without sunscreen).
  • Vitamin D-rich foods include egg yolks, dairy products (cheese, butter and cream), fatty fish (tuna, salmon and mackerel) and oysters.
  • It is impossible to get the right amount of vitamin D your body needs from food. The best way to obtain sufficient vitamin D is through sunlight and/or dietary supplements.
  • A minimum concentration of 25(OH)D should be 50 nmol/L, and, for maximum bone health and prevention of many chronic diseases, the 25(OH)D concentration should be 78-100 nmol/L.
  • An intake of 800-1200 IU/d (20-30 mcg/d) vitamin D3 is required to bring the group mean 25(OH)D concentration to 75-80 nmol/L.
  • 1 IU = 0.025 µg vitamin D3 or 0.005 µg 25(OH)D.
    40 IU vitamin D3 = 1 μg vitamin D3.
    2.5 nmol/L serum 25(OH)D = 1 ng/mL serum 25(OH)D.
  • In general, 100 IU (2.5 µg) of vitamin D3 daily can raise serum 25(OH)D concentrations with 1 ng/mL (2.5 nmol/L) after 2 to 3 months.
  • 1,25(OH)2D interacts with its vitamin D receptor in target tissues to enhance intestinal calcium absorption, mobilize calcium from the skeleton and have a wide range of other genomic effects.
  • The active form of vitamin D, 1,25-dihydroxyvitamin D or calcitriol is made in many different tissues, including colon, prostate and breast.
  • Vitamin D stimulates insulin secretion.
  • Vitamin D deficiency can lead to osteoporosis in adults or rickets in children.
  • The half-life of vitamin D in the liver is approximately 3 weeks.
  • 25(OH)D or 25-hydroxyvitaminD3 or calcidiol shows a half-life of 15 days and circulates at a concentration of 25-200 nmol/L.
  • 1,25(OH)D has a half-life of 15 hours and therefore not suitable as an indicator of vitamin D status.
  • Serum 25(OH)D concentrations are the best indicator of determining adequacy because it represents the combined amounts of vitamin D synthesized in the skin and dietary sources.
  • Circulating 25(OH)D levels indicative of a deficiency state is typically defined as 25 nmol/L.
  • Vitamin D2 is approximately 30% as effective as vitamin D3 in maintaining serum 25-hydroxyvitamin D levels so up to three times as much vitamin D2 may be required to maintain sufficient levels.
    Therefore, vitamin D3 should be the preferred choice for supplementation.
  • The EFSA has set the upper tolerable level (UL) for vitamin D for adults at 4000 IU/day or 100 mcg per day.